From 2991f6205298741a9c17aa29b73a573b1e431ea8 Mon Sep 17 00:00:00 2001
From: Kurt <kaphotics@gmail.com>
Date: Mon, 28 Feb 2022 18:06:45 -0800
Subject: [PATCH] Reduce allocation for eggmove loading

---
 PKHeX.Core/Legality/Structures/EggMoves.cs | 93 ++++++++++++----------
 1 file changed, 49 insertions(+), 44 deletions(-)

diff --git a/PKHeX.Core/Legality/Structures/EggMoves.cs b/PKHeX.Core/Legality/Structures/EggMoves.cs
index 5b08a8f77..9d7a17715 100644
--- a/PKHeX.Core/Legality/Structures/EggMoves.cs
+++ b/PKHeX.Core/Legality/Structures/EggMoves.cs
@@ -24,16 +24,17 @@ namespace PKHeX.Core
             for (int i = 1; i < entries.Length; i++)
             {
                 int start = ReadInt16LittleEndian(data[((i - 1) * 2)..]) - baseOffset;
-                int end = data[start..].IndexOf((byte)0xFF) + start;
-                if (start == end)
+                var slice = data[start..];
+                int moveCount = slice.IndexOf((byte)0xFF);
+                if (moveCount == 0)
                 {
                     entries[i] = empty;
                     continue;
                 }
 
-                int[] moves = new int[end - start];
-                for (int m = start; m < end; m++)
-                    moves[m - start] = data[m];
+                int[] moves = new int[moveCount];
+                for (int m = 0; m < moves.Length; m++)
+                    moves[m] = slice[m];
 
                 entries[i] = new EggMoves2(moves);
             }
@@ -44,60 +45,64 @@ namespace PKHeX.Core
 
     public sealed class EggMoves6 : EggMoves
     {
-        private static readonly EggMoves6 None = new(Array.Empty<int>());
-
         private EggMoves6(int[] moves) : base(moves) { }
 
-        private static EggMoves6 Get(ReadOnlySpan<byte> data)
-        {
-            if (data.Length == 0)
-                return None;
-
-            int count = ReadInt16LittleEndian(data);
-            var moves = new int[count];
-            var span = data[2..];
-            for (int i = 0; i < moves.Length; i++)
-                moves[i] = ReadInt16LittleEndian(span[(i * 2)..]);
-            return new EggMoves6(moves);
-        }
-
         public static EggMoves6[] GetArray(BinLinkerAccessor entries)
         {
-            EggMoves6[] data = new EggMoves6[entries.Length];
-            for (int i = 0; i < data.Length; i++)
-                data[i] = Get(entries[i]);
-            return data;
+            var result = new EggMoves6[entries.Length];
+            var empty = result[0] = new EggMoves6(Array.Empty<int>());
+            for (int i = 1; i < result.Length; i++)
+            {
+                var data = entries[i];
+                int count = ReadInt16LittleEndian(data);
+                if (count == 0)
+                {
+                    result[i] = empty;
+                    continue;
+                }
+
+                var moves = new int[count];
+                var span = data[2..];
+                for (int j = 0; j < moves.Length; j++)
+                    moves[j] = ReadInt16LittleEndian(span[(j * 2)..]);
+                result[i] = new EggMoves6(moves);
+            }
+            return result;
         }
     }
 
     public sealed class EggMoves7 : EggMoves
     {
-        private static readonly EggMoves7 None = new(Array.Empty<int>());
         public readonly int FormTableIndex;
 
         private EggMoves7(int[] moves, int formIndex = 0) : base(moves) => FormTableIndex = formIndex;
 
-        private static EggMoves7 Get(ReadOnlySpan<byte> data)
-        {
-            if (data.Length == 0)
-                return None;
-
-            int formIndex = ReadInt16LittleEndian(data);
-            int count = ReadInt16LittleEndian(data[2..]);
-            var moves = new int[count];
-
-            var moveSpan = data[4..];
-            for (int i = 0; i < moves.Length; i++)
-                moves[i] = ReadInt16LittleEndian(moveSpan[(i * 2)..]);
-            return new EggMoves7(moves, formIndex);
-        }
-
         public static EggMoves7[] GetArray(BinLinkerAccessor entries)
         {
-            EggMoves7[] data = new EggMoves7[entries.Length];
-            for (int i = 0; i < data.Length; i++)
-                data[i] = Get(entries[i]);
-            return data;
+            var result = new EggMoves7[entries.Length];
+            var empty = result[0] = new EggMoves7(Array.Empty<int>());
+            for (int i = 1; i < result.Length; i++)
+            {
+                var data = entries[i];
+                int count = ReadInt16LittleEndian(data[2..]);
+                int formIndex = ReadInt16LittleEndian(data);
+                if (count == 0)
+                {
+                    // Might need to keep track of the Form Index for unavailable forms pointing to valid forms.
+                    if (formIndex != 0)
+                        result[i] = new EggMoves7(Array.Empty<int>(), formIndex);
+                    else
+                        result[i] = empty;
+                    continue;
+                }
+
+                var moves = new int[count];
+                var span = data[4..];
+                for (int j = 0; j < moves.Length; j++)
+                    moves[j] = ReadInt16LittleEndian(span[(j * 2)..]);
+                result[i] = new EggMoves7(moves, formIndex);
+            }
+            return result;
         }
     }
 }